YOSEMITE NATIONAL PARK (CBS SF) — Firefighters battled triple digit temperatures and gusty winds Tuesday as the River Fire, burning in the Sierra Nevada south of Yosemite National Park, grew to more than 9,500 acres, destroyed several structures and triggered mandatory evacuations in Madera County.

The fire began on Sunday and doubled in size by Monday evening. There was just 15 percent containment as of Tuesday morning.

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The fire crews — one from Alameda County — were facing a laundry list of challenges.

“Firefighters continue to aggressively attack the fire while dangerous heat persists,” Cal Fire said in a Tuesday morning update. “Low humidity, tree torching, wind driven runs and frequent spot fires continue to challenge firefighters.”

The National Weather Service has issued a heat advisory for Madera County.

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“Dangerously hot conditions,” weather service forecasters warned. “High temperatures 100 to 108 for the Sierra Nevada foothills and 102 to 108 for the Kern River Valley and the San Joaquin Valley.”

Cal Fire said the blaze broke out Sunday along Oak Grove Road and Oak Grove School Road in Mariposa County about 20 miles southwest of Yosemite and quickly spread among the tinder-dry brush, fields and trees.

As of Tuesday morning, five structures have been destroyed and several hundred remained threatened.

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More than 1,200 firefighters and support personnel were battling the fire from the ground and the air including 212 engines and 5 helicopters.